1991 5-speed, LO3 [RS] and 1991 5-speed,LB9 [B4C] use the same block, pistons,flywheel?
The LO3 RS has 32,000 miles on it and the RS B4C has over 200,000 miles. Can we use the LO3 short block with the B4C's heads,cam and injection system. Will the change keep the B4C a true B4C?

GTAFOX

 

Yes, the short blocks would be the same.

But, in the strictest sense, it wouldn't be B4C anymore because the numbers wouldn't match.

Functionally - identical.

 

Just keep the original B4C engine, and swap all the LB9 parts onto it. It will make it run great and then you can always swap back to the matching #'s block whenever.

 

The blocks are not the same the LB9 is made for a roller cam and the LO3 is not. If i was you i would take the LB9 block and rebuild it and maybe put a stroker kit in it like a 383.

 

It wont run right with out the roller cam specially since u have speed density

 

LO3 have roller cams, truck LO5s do not. All 305 TBIs in Camaros came with roller cams.

 

I have a book on tuned port injection and it says when swapping from a lo3 u cant use the same block cause they dont have roller cams.

 

that book is a crock of ****

 

well i would be surprised if my LO3 has a roller cam and lifter when i take it out.

 

A good rule of thumb: If you have centerbolt valve covers, you have a roller valve train. (in most all cases)

 

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Well thats kewl if my block is roller but i dont want to use the 305 again ne way but in his case it might be good.

 

Dude its a roller block. Im 200% sure. I've had mine apart many times.

The good rule of thumb is only applicable with passenger cars. Trucks had centerbolt valve covers but flat tappet cams.

 

Just check Helms manual and the it is a roller motor. What will we need off the LB9? Are the heads the same?Exhaust manifolds the same?Thanks for the help!

GTAFOX

 

305 TPI has better heads, exaust manifolds, and sometimes a better cam.

 

Yup and the good cam was G92 TPI's up to '90 and in 91-92 all the 305TPI's got the bigger cam.

 

Thanks for your help. If anyone can think of anything else that needs to go with the change over let me know. The change over will start Sunday.

GTAFOX